The flat panel display devices (FPD) such as liquid crystal display devices (LCD) and organic electroluminescence devices (organic EL) which require less space and are less in power consumption as compared with CRT have spread widely as image planes of computers, televisions, portable telephones, car navigation, and portable information terminals. Various optical compensation films are used in FPD for inhibition of reflection, enlargement of visual field angle, etc. For example, mention may be made of reflection inhibiting films such as anti-reflection (AR) films which comprise a multilayered optical thin films differing in refractive index to reduce the surface reflectance due to the light interference effect; polarizing films which transmit only the light of a specific vibration direction and cut-off the other lights; phase difference films which perform optical color compensation of interference colors of LCD such as STN type, TN type or the like; elliptical polarizing films comprising a polarizing film and a phase difference film which are made monolithic; visual field angle enlarging films which enlarge the visual field angle of LCD; etc.
Films having birefringence are used as these optical compensation films, and, specifically, there are used films having birefringence given by stretching polyvinyl alcohol or polycarbonate norbornene resin.
Furthermore, it is known to produce a film having birefringence by forming a film on an alignment layer from a solution containing a discotic liquid crystal compound having a site showing discotic liquid crystal phase, a site giving a hydrogen bond in the molecule and a polymerizable group, thereby to form a non-oriented layer, and then heat treating the layer for 30 seconds by a metallic roll heated to 120° C. to cause polymerization through carbon-carbon bond and orientation of the film (JP-A-2001-139950 (Example 1)).
However, there are problems that the direction of optical axis such as retardation phase axis deviates by stretching, the stretch ratio is restricted for some materials of the film, and it is difficult to optionally design the wavelength dispersion characteristics which are a kind of optical characteristics.
Moreover, according to the method of JP-A-2001-139950, since orientation must also be controlled simultaneously with polymerization, it is not necessarily easy to produce films having birefringence, and the patent publication does not disclose a method for producing films having birefringence without carrying out polymerization or a method for designing the wavelength dispersion characteristics.